1. Field of the Invention
The present invention relates to a fuel injection control apparatus and method for an internal combustion engine which is supplied with a fuel by an in-cylinder fuel injection valve for injecting the fuel into a cylinder, and a port fuel injection valve for injecting the fuel into an intake system including an intake port.
2. Description of the Prior Art
Conventionally, as this type of fuel injection control apparatus for an internal combustion engine, one described, for example, in Laid-open Japanese Patent Application No. 2003-13784 is known. In this fuel injection control apparatus, fuel injection control is conducted in the following manner. Specifically, a total amount of fuel is first calculated in accordance with an intake air amount from an in-cylinder fuel injection amount which should be injected by an in-cylinder fuel injection valve and a port fuel injection amount which should be injected by a port fuel injection valve. Next, the calculated total fuel amount is divided into an in-cylinder fuel injection amount and a port fuel injection amount to calculate the in-cylinder fuel injection amount and port fuel injection amount. Then, the amount of fuel accounting for the calculated in-cylinder fuel injection amount is injected by the in-cylinder fuel injection valve, while the amount of fuel accounting for the calculated port fuel injection amount is injected by the port fuel injection port.
Generally, a fuel is injected by opening a fuel injection valve through which a pressurized fuel is injected, so that the amount of injected fuel varies depending on the pressure of the fuel, the pressure of a site (volume) into which the fuel is injected, and the like, even if the fuel injection valve is opened for the same time period. On the other hand, the conventional fuel injection control apparatus, as described above, simply calculates an in-cylinder fuel injection amount and a port fuel injection amount. As such, in the conventional fuel injection control apparatus, the amounts of fuel actually injected from the in-cylinder fuel injection valve and port injection valve deviate from the in-cylinder fuel injection amount and the port fuel injection amount due to influences such as the pressure of the fuel, the pressure of a site at which the fuel is injected, and the like, resulting in a failure of accurately controlling the amount of fuel supplied to the internal combustion engine.